The use of boluses in the treatment of ruminants is well known in the veterinary field. Such products are often weighted by a heavy density substance, such as iron or sand, in order to remain in the rumen to release a medicament. If sustained release coatings are present, the release is gradual until the source of medicament is exhausted. Exemplary of such prior art practices are German Patent No. 1,117,825, U.S. Pat. Nos. 3,507,952 or 3,056,724 and Chem. Abst. 76 108074K (1972).
While the delayed action assembly of the present invention resembles a ruminant bolus since it is designed to control the release of an active ingredient while remaining in the rumen in its most important embodiment, applicants believe this new delayed release assembly and devices containing it are distinct in both structure and function over this art.